Maria Goeppert-Mayer

German American physicist

• Born: June 28, 1906; Kattowitz, Germany (now Katowice, Poland)
• Died: February 20, 1972; San Diego, California

Twentieth-century German American physicist Maria Goeppert-Mayer shared the Nobel Prize in Physics in 1963 for discoveries related to the structure of the nuclear shell. She was the first woman to win the Nobel Prize for theoretical physics.

Primary field: Physics

Specialties: Theoretical physics; atomic and molecular physics; nuclear physics

Early Life

Maria Goeppert-Mayer was born Maria Goeppert on June 28, 1906, in Kattowitz, Germany (now Katowice, Poland). She was the only child of Maria Wolff Goeppert and Friedrich Goeppert. Her father, a physician, was also the sixth generation of professors in the family; lacking a son, he told Goeppert-Mayer that she was expected to follow the family tradition. When Goeppert-Mayer was four years old, her family moved to Göttingen, Germany, and Dr. Goeppert accepted a teaching position at the university there.

Goeppert-Mayer attended a private school that prepared women for the university entrance exam. Due to post–World War I inflation, however, the school closed. Against the advice of their former teachers, Goeppert-Mayer and four other young women from the school took the university entrance exam a year early and passed. Goeppert-Mayer matriculated at the University of Göttingen in 1924. At that time, less than ten percent of German university students were women, compared to about thirty percent in United States. Goeppert-Mayer did well at the university, making friends with some of the leading physicists there. She had expected to concentrate her studies in mathematics but became interested in physics after learning about quantum mechanics.

In 1927, Dr. Goeppert died. His widow took in student boarders, as many in Göttingen did, to help make ends meet. One of the boarders in the Goeppert home was Californian physical chemist and Rockefeller fellow Joseph Edward Mayer. He and Goeppert-Mayer were married on January 19, 1930.

Goeppert-Mayer graduated with a doctorate in theoretical physics later that year, having completed her dissertation on the theoretical treatment of double-photon processes. After she received her degree, she and her husband moved to the United States, where Mayer worked in the chemistry department at Johns Hopkins University in Baltimore, Maryland. The couple later had two children, Maria Ann and Peter Conrad. Goeppert-Mayer became a naturalized US citizen in 1933.

Life’s Work

Despite her education, Goeppert-Mayer was hired not to teach but to assist another professor at Johns Hopkins with his German correspondence. With the Great Depression affecting employment, academia tended toward anti-nepotism; jobs went to men but not to their wives. This pattern continued for Goeppert-Mayer in 1939, when Mayer accepted a position at Columbia University in New York City. She taught at Sarah Lawrence College, just outside of the city, and in the spring of 1942 began working at the Substitute Alloy Materials (SAM) Laboratory at Columbia University. Under the direction of American physical chemist Harold Urey, the SAM project studied uranium isotopes, specifically how to separate U-235 from natural uranium in order to create an atomic bomb. Goeppert-Mayer was forbidden to speak of her work.

Although Goeppert-Mayer’s research did not contribute directly to the development of the atomic bomb, she investigated related problems. She later referred to her time at SAM as key to her being regarded as a scientist with work independent from that of her husband. The couple had previously written a textbook, Statistical Mechanics (1940). On the title page, Goeppert-Mayer was listed as “Lecturer in Chemistry, Columbia University”; most people, however, did not realize the extent of her contribution to the text.

It was not until 1946 that Goeppert-Mayer became a professor. The Mayers moved to Chicago, Illinois, where Mayer had accepted professorships at the University of Chicago’s chemistry department and the university’s Institute for Nuclear Studies at the Argonne National Laboratory, and Goeppert-Mayer volunteered both at the institute and in the university’s physics department as an associate professor of physics. Despite her teaching load, she did not receive a salary because of the rules against hiring both husband and wife as faculty.

At the institute, Goeppert-Mayer began studying nuclear physics, about which she had previously known little. In the 1930s, Danish physicist Niels Bohr had likened the structure of an atom’s nucleus to a drop of liquid to explain the properties of stable nuclei. Scientists in the 1940s, following Bohr’s model, had little interest in what Hungarian American physicist Eugene Wigner at that time called “magic numbers”—atoms with nucleons (protons or neutrons) numbering 2, 8, 20, 28, 50, 82, or 126, which have an unusual stability. Although Goeppert-Mayer did not discover these numbers, she sought to explain them. In studying why nuclei with these magic numbers are more stable than others, she developed the nuclear spin-orbit coupling theory in 1948, after Italian American physicist Enrico Fermi suggested the idea.

The spin-orbit theory proposes that the nucleon has different energies when spinning around the center of the nucleus in either the same or the opposite sense. Goeppert-Mayer came up with an analogy for understanding this concept: different amounts of energy are used when dancing a fast waltz, depending on both the direction in which the dancers are spinning and the direction in which they are circling the room. Similarly, every nucleon has both a spin momentum and an orbital momentum, and the orbits are in “shells,” with one shell orbiting inside another. The vectors of the spin and the orbit are generally parallel and thus are said to have a strong coupling. The theory also explains why some elements have an abundance of isotopes. Fermi refused to take any credit for the theory but began teaching it in his classes the following week.

Goeppert-Mayer waited to publish a paper on her theory, aware that others were working on shell theory as well. Her husband, however, convinced her to complete her work. The theory was published as two papers in the journal Physical Review in 1950.

Austrian physicist Hans E. Suess and German physicists J. Hans D. Jensen and Otto Haxel developed the theory independently, which Goeppert-Mayer regarded as confirmation of her ideas. While she had gathered the experimental data herself, Jensen was aided by Haxel and Suess. Jensen and Goeppert-Mayer met in 1950, when the Mayers traveled to Europe for the US State Department. The following year, Jensen suggested that he and Goeppert-Mayer collaborate on a book about their discovery. In 1955, they published Elementary Theory of Nuclear Shell Structure, most of which was written by Goeppert-Mayer.

In 1960, the University of California, San Diego offered both Mayers full professorships. That fall, Goeppert-Mayer had a stroke, but she continued to push herself. In 1963, she shared the Nobel Prize in Physics with Wigner and Jensen. She was the only woman of nine Nobel Prize winners on the platform.

In addition to the Nobel Prize, Goeppert-Mayer also received honorary doctorates from Mount Holyoke, Smith, and Russell Sage Colleges. She was a member of the Akademie der Wissenschaften, located in Heidelberg, Germany, as well as of the US National Academy of Sciences. Goeppert-Mayer died on February 20, 1972, following a heart attack.

Impact

Goeppert-Mayer’s 1930 dissertation proposed that an electron orbiting an atom’s nucleus would, when jumping to a closer orbit, give off two photons of light. This theory was not proved experimentally until the 1960s. Her theory on nuclear spin-orbit coupling and the resulting nuclear shell model, on the other hand, quickly received recognition. Her and her colleagues’ work on shell theory changed the way scientists perceived the structure of the atom, and the shell model remains in use. Atomic shell theory has implications for comprehending nuclear structure, low-energy quantum chromodynamics (QCD), and quarks, which are the smaller components of nuclei. Nuclear physicists have also expanded upon Goeppert-Mayer’s magic numbers and used them to construct a silicon isotope with double the amount of neutrons to protons.

Goeppert-Mayer was the second woman to receive the Nobel Prize in Physics, after Marie Curie, and the first to receive the award for theoretical physics. She was the third woman to receive a Nobel Prize in the sciences overall. Goeppert-Mayer’s perseverance in conducting research in a male-dominated field, despite its barriers against women, set an example for women working in the sciences. Since 1986, the American Physical Society has offered an annual Maria Goeppert Mayer Award to women physicists who are just beginning their careers. The award includes a stipend and travel expenses for public speaking events.

Bibliography

Burkhardt, Charles E., and Jacob Leventhal. Topics in Atomic Physics. London: Springer, 2010. Print. Includes information about spin theories of the atom. Bibliography, index.

Byers, Joan, and Gary Williams, eds. Out of the Shadows: Contributions of Twentieth-Century Women to Physics. New York: Cambridge UP, 2010. Print. Includes several pages of biographical information on Goeppert-Mayer, written by a former student. Name and subject index.

Des Jardins, Julie. The Madame Curie Complex: The Hidden History of Women in Science. New York: Feminist, 2010. Print. Discusses the ways in which women have been overlooked in science, using the lives of major women scientists to highlight barriers. Illustrations, notes, index.

Ferry, Joseph P. Maria Goeppert Mayer: Physicist. Philadelphia: Chelsea House, 2003. Print. Covers Goeppert-Mayer’s life and work. Part of the Women in Science series. Illustrations, chronology, bibliography, index.

McGrayne, Sharon Bertsch. Nobel Prize Women in Science. 2nd ed. Secaucus, NJ: Carol, 1998. Print. Biographies of Nobel medalists, including photographs. Classes Goeppert-Mayer in the “second generation” of women to be awarded the prize. Illustrations, bibliography, index.